Study Of Equivalent Mechanical Model For Cassini Tanks With Fluid-structure Interaction

Aerospace technology is increasing so fast in recent years,that the spacecraft should carry mush fluid propellant,and the volume of Cassini tank is much bigger.The rigid rank model can not give a good result to fluid-structure interaction system.So this paper will do some research on the dynamics of the fluid-structure interaction system considering the flexibility of Cassini tank and support structures.Finally,a method of equivalent modeling for fluid-structure interaction system is built,which is useful in space engineering.The main contents and conclusions of this paper are listed below.The numerical model of the flexible Cassini tank with fluid is established.The vibrating frequencies and modes of fluid and tank are analyzed.The conclusions are drawn that the fluid vibrations lie in lower frequency band,the tank vibrations lie in mush higher frequency band,and the two bands are quite widely separated.Based on the beam-ring finite element method,a beam form equivalent mechanics model is built for the flexible Cassini tank with fluid and then the vibrating characteristics are analyzed.Also,an experiment is conducted to test the vibrating characteristics of tank with fluid.By comparison,the results from beam form equivalent mechanics model is in good agreement with the experiment results.The mass-spring and pendulum equivalent mechanics model formula of fluid sloshing in Cassini tank are derived.Combining the beam form equivalent mechanics model for the tank with fluid,a coupled equivalent mechanics model considering fluid-structure interactions is built.Based on the equivalent numerical model,the transient response analysis for spacecraft assembly is done.By comparing with the results from fine model,the accuracy of equivalent numerical model is tested.In conclusion,based on the analyses of the dynamics characteristics for the tank with fluid,a coupled equivalent mechanics model of fluid-structure interactions system combining the beam form equivalent mechanics model and pendulum equivalent mechanics model is proposed.The results in this paper can do some practical help in space engineering.